Digital three-dimensional manufacturing, also known as digital additive manufacturing, is a process of making a three-dimensional solid object from a digital model of virtually any shape. Three-dimensional printing is an additive process in which one or more printheads eject successive layers of material on a substrate in different shapes. Three-dimensional printing is distinguishable from traditional object-forming techniques, which mostly rely on the removal of material from a work piece by a subtractive process, such as cutting or drilling.
The production of a three-dimensional object with these printers can require hours or, with some objects, even days. One issue that arises in the production of three-dimensional objects with three-dimensional object printers that use printheads having inkjets that eject drops of material to form the objects is consistent functionality of the inkjets. During printing of an object, one or more inkjets can deteriorate by ejecting the material at an angle, rather than normal, to the printhead, ejecting drops that are smaller than an inkjet should eject, or by failing to eject any drop at all. If these inkjet deficiencies are sufficiently numerous, they can result in inaccurately formed object features. Once such inaccurately objects are detected, the printed objects are scrapped and restorative procedures are applied to the printheads to restore inkjet functionality. The print job can then be repeated. An apparatus that enables detection of inaccurately formed objects while printing would enable restorative procedures to be applied during object printing so a properly formed object could be produced. In this manner, product yield for the printer is improved and its printing is more efficient.